DESCRIPTION (provided by investigator): This is a revised application for an R01 grant entitled: Brain function predictors and outcome of weight loss and weight loss maintenance. Obesity rates are on the rise and associated with serious public health consequences and rising health care costs. Eating behavior is influenced by a convergence of processes in the brain, including homeostatic factors and motivational and reward processing. Motivational and reward processing are especially important contributors to overeating in humans. Our initial functional imaging studies have identified brain regions that respond differently to visual food cues in obese and healthy weight individuals, and are positively correlated with reports of hunger in obese participants. While shedding some light on mechanisms of overeating, many important questions remain. For instance, it is not yet known whether brain activation patterns change after dieting, or if they change differentially in successful and unsuccessful dieters. In addition, little is currently understood regarding biological processes that contribute to long-term maintenance of healthy weight. We will scan obese and healthy weight participants with a food motivation fMRI paradigm during a baseline state and after obese participants have completed a twelve- week diet-based weight loss intervention. Obese participants will then be followed though a 6-month weight maintenance period. The study will address three Specific Aims: 1. Characterize brain activation underlying increased food motivation and impulsive eating in obese individuals. 2. Identify brain activation changes and predictors of initial weight loss. 3. Identify brain activation predictors of weight loss maintenance. Findings from this study will have significant implications for understanding mechanisms of obesity, weight loss, and weight maintenance, and may ultimately lead to more effective interventions. PUBLIC HEALTH RELEVANACE: Results of this work are highly significant to public health and could lead to a better understanding of how differences in brain activation relate to obesity. Dietary interventions, while generally effective, do not work for everyone, and weight regain is a significant problem. Findings from this study will have significant implications for understanding mechanisms of obesity, weight loss, and weight maintenance, and may ultimately lead to more effective interventions.